Soil material, method for designing soil material and method for producing soil material

Abstract

To provide a soil material that allows understanding of carbon storage effects and maintains good plant growth conditions, to provide a method for designing soil material and to provide a method for producing soil material.SOLUTION: A soil material is a mixture of planting soil and biochar. The planting soil is set based on the growth characteristics of a plant species to be planted and the environmental conditions in which it will be installed. The mixing ratio of the biochar raw material to the planting soil is set based on at least one of the growth characteristics of the plant species to be planted and the planting soil. The soil material has aggregate structure which is set in such a manner that the carbon storage effect of the biochar meets specified requirements.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a soil material mixed with biochar having a carbon storage effect, a method for designing the soil material, and a method for manufacturing the soil material. [Background technology]

[0002] Traditionally, carbon dioxide absorption and storage technologies, such as biomass carbonization and soil carbon storage, have been desired as climate change countermeasures. Biochar is made from organic matter (biomass) such as bamboo and wood, which is carbonized by heat treatment at 350°C or higher in an oxygen-free or low-oxygen environment. Because biochar is primarily composed of amorphous carbon, mixing it into soil contributes to carbon storage by semi-permanently trapping atmospheric carbon dioxide fixed by photosynthesis within the soil. Biochar mixing efforts can be credited under the domestic J-Credit Scheme and on overseas trading markets, and can be traded according to the amount mixed and the carbon content, which varies depending on the raw material.

[0003] Biochar can also be used as a soil conditioner, offering multiple benefits, including improved water and fertilizer retention, neutralization, and increased soil microbial activity. It also has the advantage of being durable and water-repellent, making it easy to use as a water-retaining material. While biochar has traditionally been used as an agricultural material, there has been growing interest in its use as a soil conditioner that also has the aforementioned carbon storage effect (see, for example, Non-Patent Document 1).

[0004] However, the soil improvement effect of biochar varies depending on the biochar raw material, the amount of biochar mixed, and the type and quality of the planting soil. Additionally, the impact of biochar mixing on plant growth varies depending on the plant species. For example, some biochar raw materials have a high pH, ​​and mixing them can cause poor growth in plant species that are sensitive to alkaline soil. Therefore, the biochar mixing conditions must be determined taking into consideration both the planting soil and the plant species (see, for example, Non-Patent Document 2).

[0005] Regarding the soil improvement and carbon storage effects of biochar, a methodology for evaluating and providing data based on three categories: biochar characteristics, farmland area and type, and crop variety and yield has been published (see, for example, Patent Document 1). By using this methodology, it is expected that it will be possible to formulate biochar mixing conditions for existing farmland.

[0006] On the other hand, conventional planting soils containing biochar include soil for lawns containing bamboo charcoal and sand (see, for example, Patent Document 2) and fertilizer made from charcoal compost (see, for example, Patent Document 3). [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] Ministry of Agriculture, Forestry and Fisheries, Agriculture, Forestry and Fisheries Technology Council website, "Development of CO2 reduction and absorption technologies in the food, agriculture, forestry and fisheries industries," [online], [Retrieved January 18, 2023], Internet<URL:http: / / www.affrc.maff.go.jp / docs / gikikin / attach / pdf / gikikin-1.pdf> [Non-patent document 2] Ministry of Agriculture, Forestry and Fisheries website, Global Warming Countermeasures, "Survey on the effects of charcoal application with soil carbon storage effect on crop growth," [online], [Retrieved January 18, 2023], Internet<URL:http: / / www.maff.go.jp / j / seisan / kankyo / ondanka / attach / pdf / biochar01-1.pdf> [Patent documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2022-153012 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-48708 [Patent Document 3] Japanese Patent Application Laid-Open No. 2012-139108 Summary of the Invention [Problem to be solved by the invention]

[0009] When using biochar in new planting projects, such as artificial ground green spaces in urban areas, three key points are important: soil improvement through biochar mixing, ensuring plant growth, and quantifying the carbon sequestration effect. However, conventional planting soil containing biochar has limited applications, making it difficult to meet all three requirements. Furthermore, if biochar is mixed only into the surface layer of the planting soil, the water retention effect may be limited, and lightweight biochar may be dispersed. Although a more uniform mixture of biochar and planting soil would likely have a greater soil improvement effect, the current mainstream method is to mix biochar directly into the surface layer, as in agricultural soil. Therefore, there is a need for a biochar-mixed soil material that can be used under conditions that do not negatively affect plant growth and that allows for the carbon sequestration effect to be estimated in advance, depending on the raw material and the amount mixed.

[0010] The present invention has been made in view of the above, and aims to provide a soil material that allows the carbon storage effect to be grasped and that maintains good plant growth conditions, a method for designing the soil material, and a method for manufacturing the soil material. [Means for solving the problem]

[0011] In order to solve the above-mentioned problems and achieve the object, the soil material of the present invention is a soil material comprising a mixture of planting soil and biochar, wherein the planting soil is set based on the growth characteristics of the plant species to be planted and the environmental conditions in which it will be installed, and the mixing ratio of the biochar raw material to the planting soil is set based on at least one of the growth characteristics of the plant species to be planted and the planting soil, and the biochar has an aggregate structure set so that the carbon storage effect of the biochar meets specified requirements.

[0012] In addition, the soil material design method of the present invention is a method for designing the above-mentioned soil material, and is characterized by having the steps of extracting biochar raw materials and mixing ratios that are suitable for the growth characteristics of a plant species and the planting soil, calculating the carbon storage effect of the biochar based on the extracted biochar raw materials and mixing ratios, and setting the biochar raw materials and mixing ratios based on the calculated carbon storage effect.

[0013] In addition, the method for producing soil material according to the present invention is a method for producing soil material using the above-mentioned soil material design method, and is characterized by having a step of mixing a set raw material, biochar, and planting soil at a set mixing ratio to produce soil material having an aggregate structure. [Effects of the Invention]

[0014] The soil material of the present invention is a soil material comprising a mixture of planting soil and biochar, wherein the planting soil is set based on the growth characteristics of the plant species to be planted and the environmental conditions in which it is placed, and the mixing ratio of the biochar raw materials to the planting soil is set based on at least one of the growth characteristics of the plant species to be planted and the planting soil, and the biochar has an aggregate structure set so that the carbon storage effect of the biochar meets specified requirements.Therefore, by setting the type of planting soil, the biochar raw materials, and the mixing ratio to be suitable for plant growth, it is possible to grasp the carbon storage effect and maintain good plant growth conditions.

[0015] Furthermore, the soil material design method of the present invention is a method for designing the above-mentioned soil material, and includes the steps of extracting biochar raw materials and mixing ratios that are suitable for the growth characteristics of a plant species and the planting soil, calculating the carbon storage effect of the biochar based on the extracted biochar raw materials and mixing ratios, and setting the biochar raw materials and mixing ratios based on the calculated carbon storage effect. This has the effect of making it possible to grasp the carbon storage effect and efficiently design soil materials that maintain good plant growth conditions.

[0016] Furthermore, the method for producing a soil material according to the present invention is a method for producing a soil material using the above-mentioned soil material design method, and includes a step of mixing a set raw material, biochar, and planting soil at a set mixing ratio to produce soil material with an aggregate structure, thereby achieving the effect of being able to grasp the carbon storage effect and efficiently produce soil material that maintains good plant growth conditions. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a flow chart showing an embodiment of a soil material, a method for designing a soil material, and a method for producing a soil material according to the present invention. [Figure 2] FIG. 2 is an image diagram showing an example of data in the database. [Figure 3] Figure 3 is an image of packaging soil materials. [Figure 4] FIG. 4 is a flow diagram illustrating an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the soil material, the method for designing the soil material, and the method for manufacturing the soil material according to the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to these embodiments.

[0019] A soil material according to an embodiment of the present invention is a soil material comprising a mixture of planting soil and biochar, the planting soil being determined based on the growth characteristics of the plant species to be planted and the environmental conditions in which the planting soil will be placed, the biochar raw material and the mixing ratio relative to the planting soil being determined based on at least one of the growth characteristics of the plant species to be planted and the planting soil, and the biochar has an aggregated structure that satisfies predetermined requirements for the carbon storage effect of the biochar. According to this embodiment, by determining the type of planting soil, the biochar raw material, and the mixing ratio appropriate for plant growth, the carbon storage effect can be grasped and the plant can be maintained in good condition.

[0020] The method for producing the soil material according to this embodiment consists of four processes: 1) examining the combination of biochar and planted soil based on a database, 2) calculating the carbon storage effect, 3) creating a soil mixture of biochar and planted soil, and 4) packaging the soil material, as shown in Figure 1. The specific details of each process are explained below.

[0021] 1) Examination of combinations of biochar and planting soil based on the database First, we consider the biochar mixing conditions that will not cause poor plant growth, taking into account the plant species, biochar raw materials and production methods, and biochar introduction conditions. For example, by utilizing existing knowledge, such as the carbon storage agriculture evaluation system described in Patent Document 1, and by conducting literature research, we will create a database of planting soil types and biochar raw materials and mixing amounts suitable for each plant species' growth characteristics (Step S1). Figure 2 shows an example of the database data. Planting soil should be selected taking into account the presence or absence of load restrictions on the artificial ground, necessary nutrients, and the type of surrounding soil. Plant species can include crops primarily cultivated in Japan, as well as native herbs frequently used in landscaping.

[0022] Next, biochar mixing conditions are examined for each plant species based on the database, and the compatibility of the mixing conditions is evaluated to ensure plant growth is not impaired (Step S2). Evaluation can be performed, for example, based on yield. As a result, those evaluated as compatible are extracted and listed as candidates for biochar mixing conditions (Step S3). Meanwhile, those evaluated as incompatible are excluded from the candidates (Step S4).

[0023] After step S3, the soil conditions (weight, volume, etc.) of the target soil are considered (step S5), and the biochar mixing conditions are examined for each soil condition, and whether the mixing conditions are compatible with the target soil conditions is evaluated (step S6). As a result, those evaluated as compatible are extracted and listed as candidates for biochar mixing conditions (step S7). On the other hand, those evaluated as incompatible are excluded from the candidates (step S8).

[0024] 2) Calculation of carbon storage effect Next, the carbon storage effect is calculated for the candidate biochar mixing conditions listed based on the database in 1) above (step S9). For the calculation, for example, the following formula is used in the J-Credit Scheme: [Carbon dioxide storage] = {[Amount of biochar applied] x [Carbon content] x [100-year survival rate of biochar] x 44 / 12} - {Emissions related to the transportation, production, etc. of biochar} It can be calculated using the formula:

[0025] Among the candidate mixing conditions, the condition with the highest calculated carbon storage amount is given priority. That is, it is determined whether the calculated carbon storage amount is equal to or greater than a predetermined threshold value. As a result, if the calculated carbon storage amount is equal to or greater than the threshold value, the mixing condition (condition with high carbon storage amount) is adopted as the design mix, and the process proceeds to the next step S11. It is desirable to adopt the mixing condition that maximizes the carbon storage effect according to the growth characteristics of the plant species to be introduced. On the other hand, the mixing condition (condition with low carbon storage amount) that is not equal to or greater than the threshold value is excluded from the candidates (step S10).

[0026] 3) Mixing biochar and planting soil Next, a mixed soil is prepared (manufactured) by mixing the biochar and planting soil (Step S11). The planting soil should be selected based on the building's load restrictions and other installation conditions. Because small particles tend to settle at the bottom due to gravity, it is preferable to use biochar and planting soil with relatively similar particle sizes. Furthermore, to ensure water retention, it is effective to form an aggregated structure, which is an aggregate of particles, to create voids between the particles. Therefore, it is desirable to add organic matter and soil microorganisms necessary for the formation of the aggregated structure to the mixed soil (Step S12) and cover and cure it for a predetermined period (e.g., one month or more). Furthermore, from the perspective of resource reuse, it is preferable to use pruned branches and leaves generated during the biochar production process and compost them as organic matter, if possible.

[0027] 4) Packaging of soil materials Next, the planting soil and biochar are mixed together and packaged as a soil material. At this time, as shown in Figure 3, the carbon storage amount for each biochar mixing condition is clearly indicated on the package based on the results of step 2) above (Step S13). The example shown in the figure shows a case where the carbon storage amount per 10 L of soil material contained in the package is 50 g. This allows for the production of soil material that claims to have a carbon storage effect (Step S14).

[0028] According to this embodiment, the carbon storage effect of biochar is stated on the packaging, allowing users to use it for crediting purposes without having to calculate it themselves. Furthermore, because the planting soil and biochar are pre-mixed under optimal conditions and the resulting mixed soil has an aggregated structure, the risk of poor plant growth is low. Furthermore, biochar-mixed soil can be selected according to installation conditions, including building load restrictions.

[0029] (Example) Next, an embodiment of the present invention will be described. Figure 4 shows a specific example of soil selection when Miscanthus sinensis is selected as a grass species suitable for alkaline soil, and artificial lightweight soil is selected as the soil. As shown in this figure, we used a database to consider biochar mixing conditions and evaluated the biochar mixing conditions for each plant species (Steps T1 and T2). We then listed candidate mixtures with a wood or bamboo charcoal mixture ratio of 20% or more (Step T3). Therefore, we eliminated mixtures with a wood or bamboo charcoal mixture ratio of less than 20% from the candidates (Step T4).

[0030] Next, the soil conditions (weight, volume, etc.) of the target site were determined as follows: rooftop green soil (60 kgf / m 2 Taking into consideration the difference in soil content (within 70%) (Step T5), the biochar mixing conditions for each soil condition were evaluated (Step T6). In the case of black soil, mixing rates of less than 70% were listed as candidates (Step T7). Therefore, black soil mixing rates of 70% or more were excluded from the candidates (Step T8).

[0031] Next, the carbon dioxide storage capacity is calculated (Step T9), and the mixing conditions with high storage capacity are adopted and the conditions with low storage capacity are excluded. In this example, the condition with low biochar mixing rate and high weight was excluded (Step T10).

[0032] Next, biochar and planted soil are mixed under the selected mixing conditions (Step T11), and organic matter and microorganisms are added to form an aggregate structure (Step T12). In this example, the mixture was 30% bamboo charcoal, 40% artificial lightweight soil, 20% perlite, and 10% leaf mold by mass. The resulting soil material is packaged and the storage volume is clearly indicated (Step T13). This process allows for the production of soil material with carbon storage effects (Step T14).

[0033] As described above, the soil material of the present invention is a soil material comprising a mixture of planting soil and biochar, wherein the planting soil is set based on the growth characteristics of the plant species to be planted and the environmental conditions in which it will be placed, and the mixing ratio of the biochar raw materials to the planting soil is set based on at least one of the growth characteristics of the plant species to be planted and the planting soil, and the biochar has an aggregate structure that is set so that the carbon storage effect of the biochar meets specified requirements. Therefore, by setting the type of planting soil, the biochar raw materials, and the mixing ratio to be suitable for plant growth, it is possible to grasp the carbon storage effect and maintain good plant growth conditions.

[0034] Furthermore, according to the soil material design method of the present invention, a method for designing the above-mentioned soil material includes the steps of extracting biochar raw materials and mixing ratios that are suitable for the growth characteristics of a plant species and the planting soil, calculating the carbon storage effect of the biochar based on the extracted biochar raw materials and mixing ratios, and setting the biochar raw materials and mixing ratios based on the calculated carbon storage effect.Therefore, it is possible to efficiently design soil materials that can grasp the carbon storage effect and maintain good plant growth conditions.

[0035] Furthermore, according to the method for producing a soil material of the present invention, a soil material is produced using the above-mentioned soil material design method, and includes a step of mixing a set raw material of biochar and planting soil at a set mixing ratio to produce soil material with an aggregate structure, thereby making it possible to grasp the carbon storage effect and efficiently produce soil material that maintains good plant growth conditions.

[0036] The Sustainable Development Goals (SDGs) are 17 international goals adopted at the United Nations Summit in September 2015. The soil material, the method for designing a soil material, and the method for manufacturing a soil material according to the present embodiment can contribute to the achievement of one of the 17 SDGs, for example, goal 15, "Conserve and preserve the richness of land." [Industrial Applicability]

[0037] As described above, the soil material, the method for designing the soil material, and the method for manufacturing the soil material according to the present invention are useful for soil materials mixed with biochar, and are particularly suitable for understanding the carbon storage effect and maintaining good plant growth conditions.

Claims

1. A soil material comprising a mixture of planting soil and biochar, The planting soil is selected based on the growth characteristics of the plant species to be planted and the environmental conditions in which it will be installed. The mixing ratio of biochar raw materials to planting soil is set based on at least one of the growth characteristics of the plant species to be planted and the planting soil, and the soil has a granular structure that is set so that the carbon storage effect of the biochar meets specified requirements.

2. 2. A method for designing a soil material according to claim 1, comprising: Extracting biochar raw materials and mixing ratios suitable for the growth characteristics of plant species and planting soil; Calculating the carbon storage effect of biochar based on the extracted biochar raw materials and mixing ratios; and determining the raw material and mixing ratio of biochar based on the calculated carbon storage effect.

3. A method for producing a soil material using the soil material design method according to claim 2, comprising: A method for producing a soil material, comprising the step of mixing a set raw material, biochar, and planting soil at a set mixing ratio to produce a soil material having a granular structure.

Images